Expansible element



Oct. 24, 1939.

c. H. HAVILL ,56

EXPANSIBLE ELEMENT Filed July 21, 1936 COPPER- v .BERYLL/UM COPPER 6 BERYLL/UM M/l/AR INVE NTOR. C/mfon ff /7m//// Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE EXPANSIBLE ELEMENT Application July 21, 1936, Serial No. 91,795

1 Claim.

This invention relates to expansible elements and particularly to expansible elements of the character employed in diaphragms or bellows to vary the volume of a chamber formed by one or more of such expansible elements, in combination with one or more relatively fixed elements, 'such as an end wall or an enclosing frame or rim.

In such devices the end wall, enclosing frame, or encircling rim, while relatively fixed, is never- 0 theless subject to at least slight movement or expansiom'as a result of either temperature or pressure changes; and an object of this invention is to prevent, or reduce to a minimum, such thermally induced movement or expansion.

5 In a pressure responsive mechanism, or aneroid, of a barometer or altimeter, a bimetallic thermostat has heretofore been employed to act upon the indicating mechanism in such a manner as to correct for the effect of temperature 30 variations on the presure responsive expansible element. It has been found, however, that the correction factor does not always function as intended due to the intervention of an additional disturbing factor, namely, the tendency of the g5 entire mechanism to shift due to expansion or contraction of the supporting frame. To overcome this difliculty I propose to employ, in lieu of such supporting frame, a disc of a metallic thereto in any suitable manner, as by welding, riveting, etc.

With the illustrative construction indicated in the accompanying drawing, which shows Fig. 1 as a transverse sectional view, and Fig. 2 as a side elevation of the device, the outer rims 4 and 5 5 of the elements 2 and 3, respectively, are held fast regardless of temperature variations, and their tendency to curl inwardly or spread outwardly, is effectively checked by virtue of the engagement with the substantially non-expanding and non-contracting disc 6. At the same time the freedom of expansion and contraction, in an endwise direction, is not restricted and remains as heretofore.

In order to maintain pressure equality on both 5 sides of the disc 6, one or more openings 1 are provided.

What I claim is:

In an aneroid, the combination with a pair of diaphragmsmovable to infinitely numerous dif- 20 ferent positions in response-to correspondingly numerous pressure changes, of means engageable with said diaphragms to hold the outer rims. thereof against movement in their own planes, said means including a metallic disc interposed 25 between said diaphragms and of substantially uniform dimensions at all temperatures, said disc being apertured to create equality of pressure on both sides thereof. 

